Process for reacting ammonia and olefins



Patented Dec. 23, 1952 PROCESS FOR REACTING AMMONIA AND OLEFINS John W.Teter and Leonard E. Olson, Chicago, Ill., assignors to SinclairRefining Company, New York, N. Y., a corporation of Maine No Drawing.Application February 11, 1949, Serial No. 75,976

3 Claims. (01. act-455.3)

This invention relates to improvements in th production ofnitrogen-containing products, particularly nitriles, by the directcatalytic reaction of olefins with ammonia. It includes improvements inthe process and particularly comprehends an improved type catalyst whichis characterized by high relative activity and catalyst life.

The production of nitrogen-containing products, particularly nitriles,by direct reaction of ammonia with olefins requires relatively hightemperatures; e. g. ranging from about 400 F. to about 725 F., elevatedpressure; e. g. upwards of 50-0 p. s. i., and the use of a catalystwhich selectively promotes amination in an environment of competingreactions such as hydrogenation, dehydrogenation, cracking, andpolymerization. The nature of the catalyst is critical, and cobaltcontaining catalysts although very costly have been found to be mostsatisfactory from the standpoint of activity, product distribution, andcatalyst life. Our application Serial No. 694,434 filed August 31, 1946,now Patent No. 2,520,181, describes certain reduced metal oxidecatalysts in which a part of the costly cobalt is replaced by anothermetal which is capable as an oxide of forming a spinel-type crystalstructure with cobalt oxide. These catalysts are much mor economicalthan the standard type cobalt catalysts, and have relatively highactivities.

We have now discovered that a catalyst representin the reduction productof mixed cobalt and magnesium oxides supported on a diatomaceous earthcarrier possesses peculiarly advantageous properties in selectivelypromoting the direct reaction of olefins and ammonia. The new typecatalyst contains from about 5 to 40 weight per cent of magnesium, up toabout 50 weight per cent of cobalt, and upwards of weight per cent ofthe carrier. Actually the catalysts are not in the metallic state, butthe probable composition after activation is perhaps a mixture ofcobalt, cobalt as cobalt oxide, magnesium oxide and silica. Thisapplication is a continuation- 1n-part of our before-describedapplication Serial No. 694,434, now Patent No. 2,520,181.

The new type catalyst may be conveniently prepared, for example, bycoprecipitation of the basic carbonates of cobalt and magnesium from asolution of the sulfates of those metals. The precipitant, for example,soda ash, is conveniently applied in solution with which the supportingmaterial, for example, celite, a commercially available diatomaceousearth, is slurried prior to admixture of the hot solutions. We havefound that such. a catalyst containing, for. example,

' 26.5% by weight of cobalt, 23% of magnesium,

" at the standard processing temperature of 700 F.

and 23.9% of celite has a relative activity of 35 Weight per centnitrile yield compared to 28% shown by a standard cobalt on celitecatalyst tested under comparable conditions. In addition,

' we have found that the useful life of the new catalyst is markedlysuperior to that of the standard catalyst. For example, in a comparisontest in which the standard catalyst and the before-described newcatalyst were held for 30 days and were then re-tested for activity, theactivity of the standard catalyst declined from an initial activity of27 to an activity of 18, whereas the new catalyst fell on" onlyslightly, from to 33.

We have found that th molar proportion of cobalt to magnesium,calculated as metal, may vary between approximately 1:2 and 1:8 withoutserious effect on cobalt efficiency; that is the relationship of yieldto weight per cent cobalt. We have found, however, that approximately10% of celite or a similar diatomaceous type material is necessary forsuperior activity on both ayield basis and a catalyst life basis. Wehave found that catalysts containing approximately 25 to 35 weight percent of cobalt, approximately 5 to weight per cent of magnesium, and say10 to 25 weight per cent diatomaceous earth are particularlyadvantageous with respect to catalyst activity and life.

The new catalysts are advantageously prepared in the form of smallagglomerates or granules, as by pelleting or extrusion, after depositionof the active'ingredients on the inert carrier, and in the process, willadvantageously be used in the form of a fixed bed, with the mixturecontaining the ammonia and olefin being passed through the bed.

The new catalysts are capable of reactivation by hydrogen after havingbeen onstream for a period of time sufiicient to cause the catalyst tolose some of its initial activity, and may be used with advantage in thecyclic process described in Teter Patent 2,419,470 issued April 22,1947, in which two or more reactors are used in parallel, with onereactor 'onstream while the other is beingreactivated by passinghydrogen through it followed by an ammonia purge. However, we have foundthat the burden of reactivation is considerably reduced because of theimproved life of the new type catalyst. In general, in usingthe newcatalyst, it is advantageous to use a large excess of ammonia in theprocess, as described in Teter Patent 2,417,892 issued March 25, 1947,and a relatively high space velocity; e. g. about 0.5 liquid volume ofolefin per volume of catalyst perhour. ,7

The new type catalyst is prepared by depositing the catalytic metal onthe inert carrier, for example, as the hydroxide or carbonate, calciningthe resulting material to convert the metal to the oxide or mixture ofoxides, and then reducing the resulting metal oxide with hydrogen. Theexact structure of the resulting reduced metal mixture is not known.That is, it is not known whether in the active catalyst, the metal ispresent as such, or whether partof it ispresent as such, with theremainder present as anoxide, or mixture of oxides, or whether theeffective catalytic material represents equilibrium mixture of metal,and oneor more metal oxides. The reduced metal catalyst is pyrophoric,and ferromagnetic, and there are.

indications that it does contain definite proportions of both metal andmetal oxide, and it may,

be that the active catalyst is metal activated by metal oxide, or theactive material may be an in: termediate oxide.

In the prepartion of the catalyst, cobalt sulfate, and the sulfate orother soluble salt of magnesium, will ordinarily be used because ofcost, but in general, the nature of the salts selected is not of greatsignificance. After the cobalt and magnesium are deposited on thecarrier in the form of the hydroxide or carbonate, the product is washedwith demineralized water to remove soluble salts, and in particular, toremove suliate and chloride ions. In general, in the new catalysts, itis desirable to keep the sulfate content below about 0.2%, and'thechloride content below about 0.1%. Sodium, in small quantities, howevermay be an activator or-promoter, so that the same care in its removal isusually unnecessary. The product is finally calcined, pelleted, andreduced. Ordinarily, final reduction will be carried out in the reactor,although it is possible to reduce the catalyst in another vessel,and'then stabilize it in the known way for transportation. A typicalpreparation and certain of the principles of our invention will beillustrated by the following examples.

Example I A suspension of 54.0 grams of diatomaceous earth (Celite #337)is slurried for 10 minutes in 1.5 gallons of a hot (90 C. approximately)solution of soda ash containing 1270 grams of anhydrous sodium carbonate(NazCoa). One gallon of a hot solution containing 895 grams of cobaltsulfate heptahydrate (CoSO4-7H2O) and 1370 grams of magnesium acetatetetrahydrate (Mg(OAC)2-4H2O) corresponding to a cobalt t magnesium moleratio of 1:2 is then added over a half hour period. The slurry isallowed to cool while stirring for an additional half hour,

and the precipitate filtered'off and dried at l10 C. for 1216 hours. Thedried precipitate is then broken up and washed with hot water by aseries of successive slurrying and filtering procedures until thesulfate analysis on the cake drops to 0.10% on an ignited'basis. Thecatalyst cake is then redried at 110 C. ground to pass 20 mesh andcalcined for 2 hours at 340 C. Ordinarily, 30 minutes is allowed inaddition for the material to come up to temperature. The calcinedmaterial is mixed with 4% graphite and pelleted. The catalyst is thenintroduced into a reactor and reduced as with hydrogen at'3,000 spacevelocity and atmospheric pressure for 5 hours, followed by an ammoniapurge at processing temperature and pressure.

The. catalyst so prepared was then used in the production ofnitrogen-containing products.

some

from a mixture of ammonia and hydrocarbon, the hydrocarbon being atypical PP fraction containing 37% of propylene with the remainderlargely propane, with some ethane, ethylene, and higher hydrocarbons.The molar ratio of ammonia to olefin in the feed was 10:1. The olefinspacevelocity was 1.0 volume per volume of catalyst per hour. Thetemperature was 700 F., the pressure 1,500 p. s. i., and the runs wereconducted in a cyclic manner over a 1-hour period. The yield ofnitrogen-containing products was 23% (average of 3 runs) with a productdistribution,relatively high in the desirable propionitrile, as follows:acetonitrile 25.2 weight per cent, propionitrile 44.5, isobutyronitrile4.4, n-butyronitrile 17.9, and water and bottoms 0.8 and 7.2.respectively.

Under comparable test conditions a standard cobalt on celite catalystcontaining approximate- 1y 39% cobalt gave an average weight per centyield over 3" testsof 28%. Thus the Co:2MgO catalyst containingonly47.5% as much cobalt gave 82% yield of the standard catalyst. Obviously,this represents a very significant advantage from the cost standpointsince cobalt is by far the most expensive ingredient in these catalysts. From the standpoint of equivalent cobalt content the catalyst ofthe example had a relative activity of compared to the standardcatalyst.

Example. II

A catalyst. having an increased cobalt and magnesium content, but. inwhich the same CozMgOratio was retained, was then prepared in ananalogous manner. The catalyst contained 26.5 weight per cent cobalt,23% magnesium, and. 23.9% celite. The activity under similar testconditions wasfound to be 35 weight per cent yield of nitrile. Thus thiscatalyst has an activity of 125% compared to the standard catalyst 100%,and on the basis of equivalent cobalt contenthad a relative activity ofWhen tested for catalyst life by holding for 30 daystothe standardcobalt-celite catalyst in terms of efiiciency of cobalt utilization;that is with respect to the relationship between yield and weight'percent cobalt with the superiority most marked'over the approximate rangeof 20 to 50 weight... per cent cobalt. The activities of the standardcobalt-celite catalyst do not increasev quite. asrapidly withincreasingweight per cent cobalt, with lower activity values obtained for eachequivalentweight per cent cobalt and the activity reaches a' maximumobtainable value at a lower figure. Thus, activities higher'thanabout,30% are not feasible with standard cobalt catalysts. asthesecatalysts'reach an optimum concentration of. cobalt at about 40Weight per cent: cobalt and. activities fall 01f rapidly as higher.concentrations of cobalt are used.

Other examples, of. useful catalysts that we have, prepared are, by wayofillustration: 4CozMg on 25% celite which displayed an activityof. 31%,C0:8Mg on 15 celite which displayed an activity of 21%, Co:2Mg on celitewhich displayed an activity of 36 weight per cent nitrile produced.These catalysts are characterized by a high efficiency of cobaltutilization combined with long catalyst life. With respect to maximumutilization of reactor volume, however, we consider that catalystscontaining approximately 25 to 35 weight per cent cobalt are especiallyadvantageous.

By contrast, a catalyst prepared Without diatomaceous earth support,containing 43.0% cobalt and 26.6 weight per cent magnesium showed aninitial activity of only 21.1% despite the high cobalt content. Evenmore significantly, however, the activity dropped to l ss than 7% afterone test and a standard reactivation in the second hour of testing.Accordingly, we consider that the presence of celite or a similar typesupport is required for good activity and catalyst life. Typical data onthe aforesaid illustrative catalyst preparations and test runs aresummarized in the following table:

Wt. Wt. Pe'cent Percent 00 Mg Wt. Percent Celite Approximate CatalystComposnion Yields 1 1 Test conditions: 700 F.; 1,500 p. s. i.;l0i1/NHa:Ca=mOie ratio; 00 minute test period; 1.0 liquid v./v./hr.olefin space velocity. 37% propyle11e=in hydrocarbon. I

2 On further testing activity fell oli rapidly.

Hence, this invention provides an improved process for producingvaluable nitrogen-containing products directly from olefins and ammoniawhich utilizes improved mixed cobalt-magnesium oxide supportedcatalysts. The catalysts provide high product yields, being particularlycharacterized by improvement in cobalt utilization, and are marked bygreatly improved stability and useful life.

We claim:

1. In a process for producing nitrogen-containing products from ammoniaand olefins, the improvement which comprises reacting a mixturecontaining ammonia and an olefin, the ammonia being present insubstantial excess, in contact with a catalyst consisting of thereduction product of mixed cobalt and magnesium oxides supported on adiatomaceous earth carrier, in which the molar proportion of cobalt tomagnesium is within the approximate range of 1:2 and 1:8, the proportionof cobalt approximates 13.7 to 35 weight per cent, the proportion ofmagnesium is less than 40 weight per cent and the carrier content is atleast about 10 weight per cent, while maintaining a reaction 6temperature within the range from about 400 to about 725 F. and apressure above about 500 pounds per square inch.

2. In a process for producing nitrogen-containing products from ammoniaand olefins, the improvement which comprises reacting a mixturecontaining ammonia and an olefin, the ammonia being present insubstantial excess, in contact with a catalyst consisting of thereduction product of mixed cobalt and magnesium oxides supported on adiatomaceous earth carrier, in which the molar proportion of cobalt tomagnesium is within the approximate range of 1:2 to 1:8, the proportionof cobalt approximates to 35 weight per cent, the proportion ofmagnesium is less than 40 weight per cent and the proportion of carrieris at least about 10 weight per cent, while maintaining a reactiontemperature Within the range from about 400 to about 725 F. and apressure above about 500 pounds per square inch.

3. In a process for producing nitrogen-containing products from ammoniaand olefins, the improvement which comprises reacting a mixturecontaining ammonia and an olefin, the ammonia being present insubstantial excess, in contact with a catalyst consisting of thereduction product of mixed cobalt and magnesium oxides supported on adiatomaceous earth carrier, in which the molar proportion of cobalt tomagnesium is within the approximate range of 1:2 to 1:8, the proportionof cobalt approximates to weight per cent, the proportion of magnesiumis less than weight per cent and the proportion of carrier is at leastabout 10 weight per cent, while maintaining a reaction temperaturewithin the range from about 400 to about 725 F. and a pressure aboveabout 500 pounds per square inch.

JOHN W. TETER. LEONARD E. OLSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,381,470 Teter Aug. '7, 19452,381,473 Teter Aug. 7, 1945 2,381,709 Apgar et al. Aug. 7, 19452,417,892 Teter Mar. 25, 1947 2,418,562 Teter Apr. 8, 1947 2,429,855Teter Oct. 28, 1947 2,467,407 Ruthrufi Apr. 19, 1949 2,468,522 TeterApr. 26, 1949 2,479,879 Teter Aug. 23, 1949 OTHER REFERENCES Taylor etal.: J. Am. Chem. $00., vol. 61, pp. 503-509 (1939).

1. IN A PROCESS FOR PRODUCING NITROGEN-CONTAINING PRODUCTS FROM AMMONIAAND OLEFINS, THE IMPROVEMENT WHICH COMPRISES REACTING A MIXTURECONTAINING AMMONIA AND AN OLEFIN,THE AMMONIA BEING PRESENT INSUBSTANTIAL EXCESS, IN CONTACT WITH A CATALYST CONSISTING OF THEREDUCTION PRODUCT OF MIXED COBALT AND MAGNESIUM OXIDES SUPPORTED ON ADIATOMACEOUS EARTH CARRIER, IN WHICH THE MOLAR PROPORTION OF COBALT TOMAGNESIUM IS WITHIN THE APPROXIMATE RANGE OF 1:2 AND 1:8, THE PROPORTIONOF COBALT APPROXIMATES 13.7 TO 35 WEIGHT PER CENT, THE PROPORTION OFMAGNESIUM IS LESS THAN 40 WEIGHT PER CENT AND THE CARRIER CONTENT IS ATLEAST ABOUT 10 WEIGHT PER CENT, WHILE MAINTAINING A REACTION TEMPERATUREWITHIN THE RANGE FROM ABOUT 400* TO ABOUT 725* F. AND A PRESSURE ABOVEABOUT 500 POUNDS PER SQUARE INCH.